Saturn will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Leo, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.
From Columbus, it will be visible between 19:22 and 07:13. It will become accessible at around 19:22, when it rises to an altitude of 10° above your eastern horizon. It will reach its highest point in the sky at 00:48, 56° above your southern horizon. It will become inaccessible at around 07:13 when it sinks below 10° above your western horizon.
2008–2009 apparition of Saturn
| 31 Dec 2008 | – | Saturn enters retrograde motion |
| 08 Mar 2009 | – | Saturn at opposition |
| 16 May 2009 | – | Saturn ends retrograde motion |
A close approach to the Earth
At around the same time that Saturn passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest and largest.
This happens because when Saturn lies opposite to the Sun in the sky, the Earth passes between Saturn and the Sun. The solar system is lined up with Saturn and the Earth on the same side of the Sun, as shown by the configuration labelled perigee in the diagram below:
When a planet is at opposition, the solar system is aligned such that the planet
lies on the same side of the Sun as the Earth. At this time, the planet makes its
perigee, or closest approach to the Earth.
Not drawn to scale.
The panels below show a comparison of the apparent size of Saturn when seen at opposition in 2009, and when it is most distant from the Earth at solar conjunction.
A comparison of the size of Saturn as seen at 2009 opposition and at solar conjunction.
In practice, however, Saturn orbits much further out in the solar system than the Earth – at an average distance from the Sun of 9.54 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.
The rings of Saturn
Saturn's rings will appear very close to edge-on at this opposition.
The graph below shows the changing inclination of Saturn's rings over time. The black line indicates their inclination to our line of sight from the Earth. A negative angle indicates that the north pole is tipped towards us, while a positive angle indicates that we see the south pole. An angle close to zero means that Saturn's rings appear close to edge on.
The red line indicates the inclination of the rings to the Sun's line of sight to the planet. Interesting phenomena can occur when the rings are very close to edge-on, if the Sun illuminates one side of the rings, while we see the other. At such times, we see the unilluminated side of the rings.
The Seeliger Effect
For a few hours around the exact moment of opposition, it may be possible to discern a marked brightening of Saturn's rings in comparison to the planet's disk, known as the Seeliger Effect.
This occurs because Saturn's rings are made of a fine sea of ice particles which are normally illuminated by the Sun at a slightly different angle from our viewing angle, so that we see some illuminated particles and some which are in the shadow of others.
At around the time of opposition, however, the ice particles are illuminated from almost exactly the same direction from which we view them, meaning that we see very few which are in shadow.
Observing Saturn
At opposition, Saturn is visible for much of the night. When it lies opposite to the Sun in the sky, this means that it rises at around the time the Sun sets, and it sets at around the time the Sun rises. It reaches its highest point in the sky at around midnight local time.
But even when it is at its closest point to the Earth, it is not possible to distinguish it as more than a star-like point of light without the aid of a telescope.
A chart of the path of Saturn across the sky in 2009 can be found here, and a chart of its rising and setting times here.
At the moment of opposition, Saturn will lie at a distance of 8.39 AU, and its disk will measure 19.8 arcsec in diameter, shining at magnitude 0.5. Its celestial coordinates at the moment it passes opposition will be:
| Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
| Saturn | 11h20m20s | 6°44'N | Leo | 0.5 | 19.8" |
The coordinates above are given in J2000.0.
Over the weeks following its opposition, Saturn will reach its highest point in the sky four minutes earlier each night, gradually receding from the pre-dawn morning sky while remaining visible in the evening sky for a few months.
The sky on 22 Nov 2024
| The sky on 22 November 2024 | ||||||||||||||||||||||||||||||||||
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48% 21 days old |
All times shown in EST.
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Source
The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
Related news
| 08 Mar 2009 | – Saturn at opposition |
| 16 May 2009 | – Saturn ends retrograde motion |
| 10 Aug 2009 | – Equinox on Saturn |
| 04 Sep 2009 | – Saturn ring plane crossing |
Image credit
© NASA/Cassini